Apparatus for adjusting inclination of chair backs

ABSTRACT

An apparatus for adjusting the inclination of a chair back, is disposed on the chassis at the bottom of a cushion and pivotally coupled to the middle of a base at the upper end of chair legs. A control rod has its middle predetermined position pivotally coupled to the base. A positioning plate has a bolt at its top surface and is disposed at the rear end of the base. A resilient component is pivotally coupled such that one end of the resilient component is hooked into an end of the control rod, and the other end of the resilient component being hooked into the bolt at the top surface of the positioning plate. When the control rod is turned to swing its end, the resilient component rotates, so that one of the resilient legs of the resilient component produces an elastic push onto the positioning plate. Thus the positioning plate contracts and moves to embed into or withdrawal from a latch groove disposed at the bottom rear side of the chassis. Therefore, the pushing force of a spring can be acted completely on the positioning plate and the positioning plate can move smoother, making operation easier and simpler.

FIELD OF THE INVENTION

The present invention relates to an apparatus for adjusting aninclination of chair backs, more particularly to an apparatus comprisinga control rod disposed on the base of a chair with a rotary end, acontractible fixing plate being slidably embedded into or withdrawn froma latch opening disposed at any position on the rear side of the chassisfixed on the bottom of a seat cushion for adjusting the inclination of achair back.

BACKGROUND OF THE INVENTION

The R.O.C. Patent No. 496133 disclosed an apparatus for controlling theinclination of a chair back, comprising: an air pressure rod disposed atthe upper end of a chair leg and having an end passing through a base; achassis with a cushion disposed on the base; the fixed base and chassisbeing pivotally coupled together; a plurality of latch grooves extendeddownward from the rear side of the chassis; a guide base disposed on thebase and having a groove for accommodating a positioning plate; asliding base slidably disposed on the top surface of the guide base; alinear long hole and an aslant long hole respectively disposed at thetop surface of the guide base and sliding base; and a screw passingthrough the long holes and mounting the guide base and sliding base ontothe positioning plate in the groove.

An ear section of a reciprocating rod passes through one side of thesliding base, and a spring is disposed on each side of the reciprocatingrod, such that both external sides of the spring are blocked by ablocking member at the end of the reciprocating rod, and one end of thereciprocating rod is fixed onto a control rod for controlling theinclination of the chair back. Therefore, when the control rod is pushedto drive the sliding base to move, and the control rod is further pushedby a resilient prestressing force of the spring and the aslant long holesuch that the positioning plate is extended into or withdrawn from thegroove to embed or withdraw the positioning plate respectively into orfrom the latch groove disposed at the end of the chassis for adjustingthe inclination of the chair back.

However, the force of the spring driving the sliding base to move isperpendicularly to the moving direction of the positioning plate, anddrives the position plate to move the long hole to an aslant position.As a result, the force for moving the positioning plate is only half ofthe force for the spring to move the sliding base. Further, the forcefor moving the positioning plate will be reduced drastically by thefriction between the sliding base and the guide base and the frictionbetween the positioning plate and the groove.

Thus, the positioning plate will be stuck into the groove easily.Although the resilience of the spring can be increased to strengthen theforce to push the positioning plate, it also requires users to apply alarger force to push the control rod. Therefore, a larger force isneeded for the operation. Since the direction of applying force tooperate the control rod and the direction of the reaction of the springhave the same axial direction, which will make the operation of thecontrol rod unsmooth and uneasy, particularly when a larger force isneeded to operate the control rod.

SUMMARY OF THE INVENTION

Making the movements of the positioning plate smoother and the operationeasier and simpler for users is exactly the objective of this invention.Therefore, the present invention adopts a power-saving lever structureto control the control rod and achieve the purpose of an easy operationand greatly enhance the force to move the positioning plate.

The present invention also designs the direction for applying a force bythe spring to push the positioning plate in the same direction as themoving direction of the positioning plate, such that the pushing forceapplied to the positioning plate by the spring can be acted completelyonto the positioning plate without any loss, and thus making themovement of the positioning plate smoother.

The technical measures adopted to achieve the foregoing objectivesinclude a base pivotally coupled to a middle predetermined position ofthe control rod, and a resilient component having two resilient legs,such that one of the resilient legs is hung at an end of the controlrod, and the other resilient leg is hooked onto the positioning plateslidably disposed on the base, and the direction of pushing theresilient leg is vertical to the moving direction of the positioningplate. Therefore, when the control rod is pushed to swing its end anddrives the resilient to rotate, one of the resilient legs pushes orpulls the positioning plate, and further moves the positioning plate toembed into or withdraw from a latch groove disposed at any position atthe bottom rear side of the chassis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the disassembled parts of the structureaccording to the present invention.

FIG. 2 is a top view of the apparatus for adjusting the inclination of achair back according to the present invention.

FIG. 3 is a cross-sectional view of a side of the apparatus foradjusting the inclination of a chair back according to the presentinvention.

FIG. 4 is a partial view of the latch member according to the presentinvention.

FIG. 5 is a view of the fixing plate being withdrawn from the latchgroove according to the present invention.

FIG. 6 is a view of the movements of adjusting the inclination of achair back according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description and technical characteristics of the presentinvention are described together with the drawings as follows.

Please refer to FIGS. 1, 2, and 3 for the present invention. Theapparatus for adjusting the inclination of a chair back comprises a base1 disposed at the upper end of a chair leg, a chassis 2 disposed at thebottom of a cushion of a chair, such that the base 1 and the chassis 2are pivotally coupled together in the middle, and the rear end of thebase 1 is pivotally coupled to a through hole 42 at the front end 41 ofa swing frame 4. A through hole 43 disposed on both sidewalls of theswing frame 4 is pivotally coupled to a link arm 23 extended from bothsides at the rear side of the chassis 2, and a positioning member 21 isfixed to the middle section of the bottom at the rear side of thechassis 2, and a plurality of latch grooves 22 is disposed on thepositioning member 21.

Further, an end of a control rod 3 is extended out from the base 1, suchthat a middle predetermined position 31 of the control rod 3 ispivotally coupled to a fixed base 11, and the fixed base 11 is mountedonto the base 1. The middle of the control rod 3 passes through thelatch member 7 (as shown in FIG. 4) fixed in the base 1. Anaccommodating groove 71 is disposed on the latch member 7 foraccommodating the rod body 35 of the control rod 3, and a blockingprotrusion 72 disposed at the middle of the accommodating groove 71 andhaving a size smaller than the rod body 35 of the control rod 3. Ahollow space is disposed in the accommodating groove to define aresilient section 73 in the middle, such that the blocking protrusion 72can have a better elastic latch action to provide a smooth movement andpositioning between both ends of the accommodating groove 71 of the rodbody 35.

Further, the control rod 3 continues to extend to define an end section32 having a through hole; a sliding groove 10 is disposed in the middleat the rear end of the base 1; and a sliding positioning plate 5 isdisposed in the sliding groove 10. Then, a cover 12 having a long hole13 at its top surface covers the positioning plate 5 and allows thepositioning plate 5 to move back and forth, and lets the front end ofthe positioning plate to be extended out into any latch groove 22 at therear side of the chassis 2. In the meantime, the positioning plate 5 hasa rod body 51 at its top surface, so that the rod body 51 passes throughthe long hole 13 of the cover 12, and then a resilient member 8 ispivotally coupled onto the cover 12 for a free rotation. The resilientmember 8 has two resilient legs 81, 82, wherein one of the resilientlegs 81 is hooked into the through hole at the end section 32 of thecontrol rod 3, and the resilient leg 82 at the other end is hooked intothe rod body 51.

Please refer to FIGS. 5 and 6. When the external end of the control rod3 is pushed, the rod body 35 at the middle section will be embedded fromone end of the accommodating groove 71 of the latch member 7 to theother, and further elastically blocks the rod body 35 by the middle ofthe blocking protrusion 72 for the positioning. In the meantime, the endsection 32 of the control rod 3 will swing to force the resilient leg 81to extend outward, such that the resilient member 8 produces a rotaryprestressing force, and the resilient leg 82 at the other end produces aprestressing force to shift the positioning plate 5 to the left.Therefore, when the chair back is pressed and released by thereciprocating actions, the positioning plate 5 originally embedded andclamped by the latch groove 22 produces a loosened gap to let thepositioning plate 5 to be withdrawn from the latch groove 22 by a pushproduced by the prestressing force of the resilient leg 82. After thechair back is adjusted to the user's desired inclination, the controlrod 3 is pushed in the opposite direction such that the end section 32swings back to the original vertical position. Then, the resilient leg82 will produce a prestressing force to push the rod body 51 to theright. When the chair back is swung to a predetermined inclination andthe positioning plate 5 is aligned with the desired latching groove 22,the front end of the chair back will snap into the latch groove 22 andlatch the chair back.

Therefore, the control rod 3 being pushed by swinging with apower-saving lever structure can greatly increase the force to push thepositioning plate 5, and the user can save power for the operation andthus making the operation easier. Since the direction of applying forceof the resilient leg 82 of the resilient component 8 for pushing thepositioning plate 5 is in the same direction as the positioning plate 5shifts, therefore the pushing force by the resilient leg 82 is actedcompletely onto the positioning plate 5 without any loss. As a result,the positioning plate 5 is pushed with a larger force, and shifts in asmoother manner.

While the invention has been described by way of example and in terms ofa preferred embodiment, it is to be understood that the invention is notlimited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

1. An apparatus for adjusting inclination of chair backs, comprising: abase pivotally coupled to a middle of a chassis; a plurality of latchgrooves disposed at a bottom at a rear side of said chassis; apositioning plate disposed at a top surface at a rear end of said basefor being slid back and forth, with an extended front end of saidpositioning plate being extended into one of the said latch grooves; acontrol rod having a middle predetermined position pivotally coupled tosaid base with an end section of said control rod being swung; and a rodbody disposed on said positioning plate and pivotally coupled to a freerotary resilient component having first and second resilient legs, withthe first resilient leg being coupled to an end of said control rod, andthe second resilient leg being hooked into a bolt disposed on saidpositioning plate; thereby when said control rod being pushed to seeingsaid end section back and forth produces a rotary prestressing force bysaid resilient component to move the position plate to selectively embedinto and withdraw from one of said latch grooves disposed at the rearside of said chassis.
 2. The apparatus for adjusting inclination ofchair backs of claim 1, wherein said base disposed at a middle of saidcontrol rod comprises a latch member having an accommodating groovethereon for letting a rod body of said control rod to pass through, anda middle of said accommodating groove is slightly smaller than aresilient blocking protrusion on the rod body of said control rod.